Original application discloses an integral extending spring 3 for resiliently opening the umbrella, which integral coil spring 3 passes through an upper tubular shaft 14 and a lower tubular shaft 11 having smaller diameter than that of the upper shaft 14. Since the integral spring 3 should pass the lower shaft 11 with smaller inside diameter and the upper shaft 14 with larger inside diameter, there will exist an aperture between the spring coil rings of the upper spring section of the spring 3 disposed inside the upper shaft 14 and an inside tubular wall of the upper shaft 14, possible causing a twisting or tangling of the spring 3 for influencing the sliding movement of the coupling 538 and the flexible rope 537, and also possibly causing noise pollution by a fictional sliding contact of the twisting spring 3 with the inside wall of the shaft 14.
Meanwhile, the restoring coil spring of the retraction restoring means 4 of the original application as shown in originally filed drawings FIG. 2, having an inner spring end 41 secured to the first top rib 21 and having an outer spring end 42 secured to an outer end of the stretcher rib 22 at a joint connected with the third top rib 24, is still obvious to the prior arts such as Yoshihara's U.S. Pat. No. 3,756,258 (the spring 8 secured between a pivotal point b and the hub member 4) and Sato's U.S. Pat. No. 3,658,077 (the compressible coil spring 7 secured to the fitting 15 and ring 6a). The restoring spring either taught by Yoshihara or Sato or even the original application filed by the present inventor is longitudinally secured between two points distantly separated, which will easily be sagged, twisted, or tangled when compressed ready for restoring operation.
The present inventor has found the drawbacks of conventional automatic umbrellas and invented the present automatic umbrella having smoothly operating springs.